The 28 cm K5 was the result of a crash program launched in the 1930s to develop a force of railway guns to support the Wehrmacht by 1939. K5 development began in 1934 with first testing following in 1936 at the Firing Test Range Rügenwalde-Bad in Farther Pomerania at the South coast of the Baltic Sea. Initial tests were done with a 150 mm barrel under the designation K5M.
Production led to eight guns being in service for the Invasion of France, although problems were encountered with barrel splitting and rectified with changes to the rifling. The guns were then reliable until the end of the war, under the designation K5 Tiefzug 7 mm. Three of them were installed on the English Channel coast to target British shipping in the Channel, and proved successful at this task.
Towards the end of the war, development was done to allow the K5 to fire rocket-assist projectiles to increase range. Successful implementation was done for firing these from the K5Vz. A final experiment was to bore out two of the weapons to 310 mm (12.2") smooth-bore to allow firing of the Peenemünder Pfeilgeschosse arrow shells. The two modified weapons were designated K5 Glatt.
Note the rifling on the shell
Several other proposals were made to modify or create new models of the K5 which never saw production. In particular, there were a number of plans for a model which could leave the railway by use of specially modified Tiger II tank chassis which would support the mounting box in much the same manner as the railway weapon's two bogies. This project was finally ended by the surrender of Germany.
Leopold after its capture by 168th Infantry Reg.
The Allied troops and sailors tended to lump all enemy guns shelling the Allied Beachead at Anzio, Italy during WWII under the nickname of “Anzio Annie” or the “Anzio Express." However, the German artillery shells hitting the beachhead were of all various calibers. And even “Anzio Annie” or the “Anzio Express," the names used interchangably by the Allies for a German 28cm K5(E) railroad gun were actually two separate guns which made up the German K-5 (E) Rail Road battery.
GI's atop Leopold in Italy
The two biggest guns shelling the beachhead at Anzio were a pair of huge, 280mm guns mounted on railroad carriages and hidden in tunnels in the Alban Hills. The Germans had named one of the guns “Leopold” and the other "Robert," but the GIs on the beachhead simply referred to them as “Anzio Annie” and the “Anzio Express," the latter because the sound of the shells flying overhead caused some soldiers to imagine a runaway train roaring through the sky. The one which the Germans called “Leopold," was located southeast of Rome near the Ciampino Airfield. The other, which they called "Robert," was situated several miles to the south of Ciampino at Frattocchio Station.
Leopold(seen in the background) shortly after its capture
Direct descendants of the 240mm railroad guns the Germans had used with such devastating effect on the western front in World War I, these two Krupp-made monsters could hurl shells packed with 550 pounds of high explosive up to thirty-eight miles. It took the German crew six to ten hours to haul the guns out of their hiding places - one was in a tunnel near Castel Gandolfo, the Pope's summer residence - and prepare them for firing. As soon as a few shells were fired, the guns were returned to their tunnels.
On June 7, 1944, the 168th Infantry Regiment of the 34th Division captured the guns on a railroad siding in the town of Civitavecchia, shortly after the allies occupied Rome. Unlike other guns where the rifling is in the barrel, on these weapons the rifling was on the shell and the bore was smooth. “Robert” had been partially destroyed by the gun crew before they surrendered and “Leopold” was also damaged but not as badly. “[i]Leopold”]being the less damaged piece and was moved to Naples and embarked aboard the liberty ship Robert R. Livingston and shipped to Aberdeen Proving Grounds (Aberdeen Maryland). The fate of "Robert" is somewhat hazy; the best guess is that it was scrapped in Italy after the war. In February of 1946, two more K-5RR guns were brought to U.S. Aberdeen Proving Ground, from Germany. Parts off those two guns were put on “Leopold” and the gun was tested at APG. One complete K5 was made from the two damaged ones, and “Leopold” remains on display to this day at the United States Army Ordnance Museum located on the Aberdeen grounds.
Note where US Forces have written "Anzio Express" on Leopold
28cm K5(E) History: The 'Leopold' and its twin the 'Robert' were of the 28cm K5(E) design. The Leopold had an unconfirmed range of 38 miles and fired a pre-engraved projectile weighing approximately 550 pounds. It is fired from a turntable affording a 360 degree traverse. The gun has a 70-foot 8-inch barrel held in a sleeve-type cradle. The barrel recoil mechanism, fitted between two arms projecting downward from the cradle, consists of two hydro-pneumatic cylinders and a single hydraulic buffer cylinder. The cradle is supported by trunnions which rest in bearings on top of a box-like frame, of gerder construction, which in tun is supported on two pintles resting in bearings in the center of two 12-wheel trucks. The front pintle bearing rides in a rail on the front truck and can be positioned six inches either side of center, thereby allowing a car traverse of approximatiely 1 degree. The equipment in effect has a double recoil action. Besides the barrel recoil which is approximaitely 32 inches, the gun car also recoils. It is coupled to the front of the turntable platform by a hydraulic buffer and a hydro-pneumatic counter-recoil mechanism which returns the car to battery position. A turntable platform is transported as part of the equipment and in transport forms a flat car with a 103-foot bed resting on two 8-wheel trucks. A central jack helps support the tremendous weight of the gun and carriage which amounts to around 230 tons and also serves as a central pivot for the turntable. The powder chamber is approximately 10 feet 5 inches long. Obturation is obtained by means of a short brass cartridge case and the breech is closed with a horizontal type of breech-block. Firing is of the percussion type.
It is hard to imagine that the Germans could conceal a weapon capable of firing a 550-pound shell. The German 28 cm K5(E) Gun was the largest weapon which lobbed shells at American troops at Anzio Beach. An aura of mystery surrounded the employment of the gun. To the bewilderment of allied officials who knew the approximate location of the Leopold, the gun could not be silenced. Repeated bomber and naval attacks failed. It wasn't until the Allies broke out of the "Anzio Beachhead" and sent the Germans scurrying that the secret was revealed. The Leopold supported by 24 rai lcar wheels, was mounted on railroad tracks which led in and out of mountain tunnels. When not firing, the gun was rolled back into the tunnels out of the sight of Allied reconnaissance. Because bombs had destroyed Italian rail systems, the Germans were forced to leave the Leopold and its twin gun "Robert" behind. Although both guns had been extensively damaged, Allied forces were able to salvage the Leopold and after reconstruction of the railway, moved the gun to Naples for shipment to the United States. "Anzio Annie" as the gun was known to the Allied troops at Anzio, is the only German railroad gun known to have survived World War II.
"Anzio Annie" - 280mm railroad gun
Railroad cannon known as "Anzio Annie" by the Americans and "Leopold" by the Germans.
Caliber: 280mm (11.02 inches)
Barrel Length: 70.08 ft
Overall Length: 135.28 ft
Shell: 563 lb High Explosive
Muzzle Veolcity: 3,700 fps
Max Range: 38 miles